83 research outputs found
Ecological implications of fine-scale fire patchiness and severity in tropical savannas of northern Australia
Research ArticleUnderstanding fine-scale fire patchiness
has significant implications for
ecological processes and biodiversity
conservation. It can affect local
extinction of and recolonisation by
relatively immobile fauna and poorly
seed-dispersed flora in fire-affected
areas. This study assesses fine-scale fire
patchiness and severity, and associated
implications for biodiversity, in north
Australian tropical savanna systems.
We used line transects to sample
burning patterns of ground layer
vegetation in different seasons and
vegetation structure types, within the
perimeter of 35 fires that occurred
between 2009 and 2011. We evaluated
two main fire characteristics: patchiness
(patch density and mean patch length)
and severity (inferred from char and
scorch heights, and char and ash
proportions). The mean burned area of ground vegetation was 83 % in the
early dry season (EDS: May to July)
and 93 % in the late dry season (LDS:
August to November). LDS fires were
less patchy (smaller and fewer
unburned patches), and had higher fire
severity (higher mean char and scorch
heights, and twice the proportion of
ash) than EDS fires. Fire patchiness
varied among vegetation types,
declining under more open canopy
structure. The relationship between
burned area and fire severity depended
on season, being strongly correlated in
the EDS and uncorrelated in the LDS.
Simulations performed to understand
the implications of patchiness on the
population dynamics of fire-interval
sensitive plant species showed that
small amounts of patchiness
substantially enhance survival. Our
results indicate that the ecological
impacts of high frequency fires on firesensitive
regional biodiversity
elements are likely to be lower than
has been predicted from remotely
sensed studies that are based on
assumptions of homogeneous burninginfo:eu-repo/semantics/publishedVersio
Importance of heterogeneity in Porhyromonas gingivalis lipopolysaccharide lipid A in tissue specific inflammatory signaling
Lipopolysaccharide (LPS) of Porphyromonas gingivalis exists in at least two known forms, O-LPS and A-LPS. A-LPS shows heterogeneity in which two isoforms designated LPS1435/1449 and LPS1690 appear responsible for tissue specific immune signalingpathways activation and increased virulence. The modification of lipid A to tetra-acylated1435/1449 and/or penta-acylated1690 fatty acids indicates poor growth conditions and bioavailability of hemin. Hemin protects P. gingivalis from serum resistance and the lipid A serves as a site for its binding. The LPS1435/1449 and LPS1690 isoforms can produce opposite effects on the human Toll-like receptors (TLR) TLR 2 and TLR 4 activation. This enabless P. gingivalis to select the conditions for its entry, survival and that of its co-habiting species in the host, orchestrating its virulence to control innate immune pathway activation and biofilm dysbiosis. Thismini review describes a number of effects that LPS1435/1449 and LPS1690 can exert on the host tissues such as deregulation of the innate immune system, subversion of host cell autophagy, regulation of outer membrane vesicle production and adverse effects on pregnancy outcome. The ability to change its LPS1435/1449 and/or LPS1690 composition may enables P. gingivalis to paralyze local pro-inflammatory cytokine production, thereby gaining access to its primary location in periodontal tissue
Team climate, intention to leave and turnover among hospital employees: Prospective cohort study
<p>Abstract</p> <p>Background</p> <p>In hospitals, the costs of employee turnover are substantial and intentions to leave among staff may manifest as lowered performance. We examined whether team climate, as indicated by clear and shared goals, participation, task orientation and support for innovation, predicts intention to leave the job and actual turnover among hospital employees.</p> <p>Methods</p> <p>Prospective study with baseline and follow-up surveys (2–4 years apart). The participants were 6,441 (785 men, 5,656 women) hospital employees under the age of 55 at the time of follow-up survey. Logistic regression with generalized estimating equations was used as an analysis method to include both individual and work unit level predictors in the models.</p> <p>Results</p> <p>Among stayers with no intention to leave at baseline, lower self-reported team climate predicted higher likelihood of having intentions to leave at follow-up (odds ratio per 1 standard deviation decrease in team climate was 1.6, 95% confidence interval 1.4–1.8). Lower co-worker assessed team climate at follow-up was also association with such intentions (odds ratio 1.8, 95% confidence interval 1.4–2.4). Among all participants, the likelihood of actually quitting the job was higher for those with poor self-reported team climate at baseline. This association disappeared after adjustment for intention to leave at baseline suggesting that such intentions may explain the greater turnover rate among employees with low team climate.</p> <p>Conclusion</p> <p>Improving team climate may reduce intentions to leave and turnover among hospital employees.</p
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